how can i syop some channels on my euro vox from jumping/skipping?

I have a euro vox max v box and some of the channels are jumping/skipping making them unwatchable how can I fix this - over the last couple of weeks the picture on the tv has become not so clear this is only when the euro vox box is in use as I have checked the standard of picture with my cable box and it is fine. Do I just need a new box? it is only about 12 months old. I am in the glasgow ntl area